820 Battery life on cold days & in general.

My battery life has been suffering as well for the past few months. Additionally, my battery indicator frequently does not move down from a reading of 100%.

Mine ok - no problems with battery life.
If I were you I'd contact Garmin Support - They might have a solution or fix it under warranty.
I allways find them very helpful.
Nick

Garmin instructed me to do master reset. Should I really?

I would - but I would backup my settings first.
https://support.garmin.com/faqSearch/en-US/faq/content/eWswdSH4aC3xrXxmQj7U9A

If the master reset doesn't help you can contact them again.

Best of luck
Nick

I would - but I would backup my settings first.
https://support.garmin.com/faqSearch/en-US/faq/content/eWswdSH4aC3xrXxmQj7U9A

If the master reset doesn't help you can contact them again.

Best of luck
Nick

Then I will do so. In the meantime Garmin have also suggested changing data save mode to "saving" mode and turning off glonass to leave only GPS as tracking system. Question to you - what will I lose by doing so? Will the tracking accuracy be still alright?

micmac24,
Just to be clear - I'm just a user of these things like you so I do not speak for (or work for) Garmin. I do not have any more expertise than many others.
1) I'm not clear what "data save mode" is.
2) Glonass should improve the accuracy at the expense of battery. See https://www8.garmin.com/manuals/webhelp/edgeexplore820/EN-US/GUID-A867FC6C-71B2-4E42-8FA5-98568D8705D3.html

I have never had a problem with battery life on my 820. My longest ride with the edge 820 so far is 138.4 miles with a moving time of 10hours 23 min in the mountains. I had Glonass on and I was navigating a route - which the Edge 820 did flawlessly. I was recording Power data and HR data from Ant+ and the 820 was connected to my Iphone via BT. The elapsed time was 12:57 - but I may have turned the edge off during some of the longer stops. Sufficient battery life for most people.

The device totals are 207 Rides, 536 hours and 12591 km.

Since having the battery run low on an Edge 800 a few years ago near the end of a 100 mile ride because I left the backlight on (and didn't notice) I run with the back light off.
I set the display time out to a minimum (15 seconds) and the Brightness to 0%.

In my experience the backlight (on these devices) drains the battery more than anything else - especially if you are flicking between pages. Every time there is an event (turn, warning or whatever) it comes on and every time you touch the screen it comes on.
The only time I use the back light is on a turbo - which I seldom do for more than an hour.
I don't know if having the backlight on is a problem with the 820 - It's just the way I use it.

I hope this helps
Nick

Thank you for sharing your expercience, Nick. I appreciate that a lot. I'm gonna apply most of the suggestions and will share experience thereafter.

You're welcome micmac24 - I hope it helps.
Nick

I'm having the same issue. Beginning around this past October battery life really started going downhill, just this Saturday I went on an 80 mile ride and ended up with 11% battery left, there's no way this thing will last a century anymore. I called Garmin support and they said they have had some calls for battery life on 820's and that they have a ticket already open which they added me to. They asked me to copy the Garmin folder to my PC, delete all file beginning with gmap, zip it and send it to them. Let's see what happens. Everyone should call so they can see this is a real problem that needs to be addressed.

Similar problem here too. I use my 820 on my daily commute. Until recently I only ever charged the device at weekends, never during the week. Now I am having to recharge after 3 days. None of my settings have changed (backlight, glonass etc) so there's no real explanation other than device software updates or the battery itself deteriorating.

I switched off auto brightness, but left the backlight always on. I'm not sure now the level, but maybe some 50% brightness. With auto brightness on, the battery gets drained in about 2-3h. With auto brightness off, it maybe 5hrs+ (not tested exactly). I assume, that the dark days cause the brightness to constantly change and very usually ends above 50%. Together with the cold weather this probably causes the quick discharge.